1. Field of the Invention
The present invention relates to novel compounds comprising a dihydropyridine basic nucleus and to the use of such novel compounds for the heat and light stabilization of a wide variety of polymers, notably PVC.
2. Description of the Prior Art
FR-A-2,239,496 describes 2,6-dimethyl-3,5-dicarboxylate-1,4-dihydropyridines as heat stabilizers for polyvinyl chloride (PVC).
EP-A-0,005,678 describes a synergistic composition of 2,6-dimethyl-3,5-dicarboxylate-1,4-dihydropyridines and .beta.-diketones for the heat stabilization of PVC.
The above 1,4-dihydropyridine compounds are highly effective for the heat stabilization of PVC. However, they are inadequate for certain applications where the polymer is subjected to outdoor exposures, i.e., when it is necessary to also have stability to light.